Dear Mr Krishnan
Thanks for your reply first.But in our case CMP is ruled
out.Since we had a very complex parent--child relationship in our
application, we did not have any other option other than opting BMP (EJB 1.1
spec) .
Any way we are in the verge of completing our project, so i wanted to know
by setting setTransactionIsolation() in my entity can i avert the
concurrency or not?.Since i tried to do that but i don't know how to
simulate the concurrent access.Hence am not able to verify.
Thanks and Regards
Saminathan.
----- Original Message -----
From: "Krishnan Subramanian" <[EMAIL PROTECTED]>
To: "SAMINATHAN" <[EMAIL PROTECTED]>
Sent: Monday, March 11, 2002 2:58 PM
Subject: RE: Re: basic transaction management and isolation level question
> Saminathan,
>
> In the case of BMP, you (that is, the developer) is responsible
> for managing concurrency and consistency of data. So, you would
> have to take the above into account if you want to write 'bullet
> proof' BMPs that are safe when accessed concurrently by multiple
> transactions.
>
> But in the case of CMP, it is as simple as turning on a flag (in
> the deployment descriptor) to tell the Container what kind of
> strategy to use. (For example you could tell it to use verified
> updates and/or you could tell it to use Oracle's syntaxt "Select
> ... For Update" for locking etc. And in the case of BMP, you'd
> have to handcode all these which takes time & effort. EJBs are
> supposed to aid developers in developing business components and
> not let the developers worry about lower level system issues such
> as persistence mechanisms and strategies. Also, if you handcode
> these - as in the case of BMP - you'd probably have to recode when
> you switch databases to one that supports a different locking
> strategy).
>
> It is best to avoid BMP. The performance of CMP is almost 2x times
> faster than its BMP counterpart. CMP code is also cleaner, more
> readable and easier to maintain & port than BMP. The Container also
> can perform optimizations - simply because it has control of when
> and what SQL code to execute (or not to execute) . But if you write
> BMP, then the Container has no control - and hence the possiblity
> of optimizing BMP code (by the Container) is reduced greatly.
>
> -krish
>
> > -----Original Message-----
> > From: SAMINATHAN [mailto:[EMAIL PROTECTED]]
> > Sent: Saturday, March 09, 2002 5:52 AM
> > To: Krishnan Subramanian
> > Subject: Re: Re: basic transaction management and isolation level
> > question
> >
> >
> > Hi Krish
> >
> > I got a chance to go thru your design pattern white paper from
> > Borlando Site.
> > The very interesting aspect in that how Borlando Managing the
Concurrency
> > issue, that's fantastic in case of CMP.
> > But i would like to know how your server will behave if it is a BMP.Will
it
> > take care by iteself. I guess no.If it is not
> > do i need to set any transaction level in SLSB or Entity.
> >
> > I am eagrly waiting for your Reply.
> >
> > Thanks and Regards
> > B.Saminathan,
> > System Analyst,
> > House of Code pvt(I) Ltd,
> > Bombay.
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